In that case I don't have added any information but I also didn't put any wrong information into the system.

You put in the information that there was a forth independent vote, when in fact there wasn't.

If a lot of people find a post useful because it helped them, I think that's a valuable signal for the person who wrote the post.

But the upvotes themselves don't affect how useful the post is, it just affects how useful you think it is.